Bacterial deposits on the surfaces of food processing equipment can lead to potential contamination of food products. Bacterial deposits on medical devices such as implants, catheters and intraocular lenses also present the potential for infection when in contact with patients and medical personnel. Consequently, good hygiene standards require that food processing equipment be thoroughly cleaned between uses and that medical and dental equipment be sterilized if possible or at least, for non-surgical instruments, thoroughly cleaned before use. Other surfaces proximate to food processing or medical equipment, such as flooring, walls, tiles, conveyor belts, drains, and packaging, also should be regularly cleaned. Nonetheless, the potential always exists for residual bacterial deposits or for the incidental growth of bacteria on cleaned surfaces, particularly after contact with biological materials as encountered in food processing, e.g., blood, fats, and proteins. For equipment that cannot be thoroughly sterilized between uses, such as most food processing equipment, the potential exists for residual bacteria surface deposits because of the tenacious adherence of bacterial biofilms to the material of the processing equipment, commonly stainless steel but also often including other metals and polymers. Biofilms are communities of microorganisms adhering to surfaces of substrates, usually within a matrix of extracellular polymeric substances. Contamination of biological origin (hereafter biological contamination) on surfaces can include biofilms, blood, proteins, fats, oils, or combinations of such materials.
It would be desirable to treat and passivate the surfaces of the materials commonly used in food processing equipment, such as stainless steel, to reduce the ability of biological contamination such as bacterial biofilm to adhere to the surface. It is known that neutral polymers like poly(ethylene glycol) (PEG), polysaccharides such as ethyl(hydroxyethyl)-cellulose, and polyglucose dextran, deposited or grafted as thin layers on various surfaces, substantially reduces protein adsorption. This capability is believed to be related to the predominant presence of C--O linkages in these synthetic and natural polymeric structures. However, it has been difficult to carry out a practical treatment of food processing equipment and many types of medical equipment to provide surface treatments that are both effective against bacterial biofilm deposit and durable.